JP 2016-131196A describes a semiconductor device having integrated resin cooler and semiconductor module provided with a resin package in which a semiconductor element is sealed. The resin package of the semiconductor module is flat, and a heat sink is exposed over its wide-width surface. The heat sink is covered by an insulating sheet, and a cooling plate is bonded to the wide-width surface of the resin package with this insulating sheet in between them. Fins are provided on an opposite side from the insulating sheet of the cooling plate. The resin cooler surrounds the cooling plate in a view along a normal direction of the cooling plate, and is bonded to both ends of the resin package in the view along the normal direction. Passages are provided inside the cooler and on both sides of the resin package in the view along the normal direction, and coolant is configured to flow along the fins of the cooler through these passages. The cooler is bonded to the both ends of the resin package and covers both sides of the cooling plate by interposing the cooling plate between itself and the resin package.
In the semiconductor device described in JP 2016-131196A, the cooling plate is constituted of metal with high heat transfer performance, such as aluminum or copper. The metal such as aluminum has quite different linear expansion coefficients from those of resin. Due to this difference in the linear expansion coefficients, stress is generated in the insulating sheet between the cooling plate and the cooler, and an edge of the cooling plate may be detached from the insulating sheet and cooling performance may thereby deteriorate. In the semiconductor device of JP 2016-131196A, the resin cooler covers the both sides of the cooling plate by interposing the cooling plate between itself and the resin package, by which detachment of the cooling plate is prevented.